Retopologizing Circular Window
I believe it's an issue with the density.



What you might want to do is start over and equal out the densities of Yellow and Red (several ways to approach this) before punching the holes to get an easier and cleaner result.

Alternatively you could add another ring and then retopo accordingly to get a cleaner hole. 

Here's a quick example (sorry for the messy image).



I used bevel on the outer ring to add another ring.

Next time, please link the mesh so it's easier for us to help you :D